Hey folks adding the correct answer to the question-Write an Apex trigger that modifies Account fields before inserting records.
Write an Apex trigger that fires before records are inserted and ensures that the ShippingState field has the same value as the BillingState field.

Here is the below code-

AccountTriggerHandler apex class-

public class AccountTriggerHandler {
    public static void CreateAccounts(List<Account> accnt){
        List<Account> act = new List<Account>();
        for(Account a: accnt){
            if(a.ShippingState!=a.BillingState){
                a.ShippingState = a.BillingState;
                act.add(a);
            }
        }
        
    }

}

AccountTrigger-trigger file

trigger AccountTrigger on Account (before insert, before update, before
    delete, after insert, after update, after delete,  after undelete) {
    if (Trigger.isBefore && Trigger.isInsert)
        AccountTriggerHandler.CreateAccounts(Trigger.new);

}

AccountTriggerTest -apex class

@isTest
public class AccountTriggerTest {
    @isTest
    public static void TestCreateNewAccount(){
        //Create 200 new accounts for billing state as CA
        List<Account> accnt = new List<Account>();
        for(Integer i=0 ; i < 200 ; i++){
            Account a = new Account(Name = 'test' +i);
            a.BillingState = 'CA';
            accnt.add(a);
        }
        
        //Perform test
        test.startTest();
        insert accnt;
        test.stopTest();
        
        //Verify test
        
        List<Account> ant = [Select Id From Account where ShippingState = 'CA' ];
        System.assertEquals(200, ant.size());
         
    }

}

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